ci(dependabot): allow bot review and extend strict gate

[jrandolf]

Why

Earl's Claude review rejects Dependabot by default. The claude-review job on #138 failed with Workflow initiated by non-human actor: dependabot, so the strict gate cannot pass. Job evidence.

The gate also ran out of time on #139, head c92ae86f17d85fcf79d5175e37815b2bc7e13594: its final MSRV (Rust 1.96) check succeeded at 18:22:28 UTC, two seconds after the gate exited at 18:22:26. Gate job.

Change

• Allow only dependabot[bot] to initiate the pinned Claude review action. Reviews still run and can still fail.
• Extend the read-only strict gate from 25 to 80 minutes of polling, with a 90-minute job limit. It still checks the unchanged exact PR head and requires every configured and applicable check to pass.

Only .github/workflows/claude-code-review.yml and .github/workflows/dependabot-automerge.yml change. No branch rule or required check is removed. Repository auto-merge remains off pending fresh bot-head checks.

Local verification

All logs and .exit files are under /Volumes/Code/Sources/.dev-storage/mathematic-inc-monitor/2026-09-24T2220Z-full-repair.PvYiXw/logs/.

Command	Exit	Log
hk check --all --slow	0	earl-hk.log
python3 scripts/release/check-state.py	0	earl-release-state.log
sh scripts/release/test-build-artifact.sh	0	earl-release-artifact.log
rustup run 1.96.0 cargo check --locked --workspace --all-features --all-targets	0	earl-msrv.log
cargo test --all-targets --all-features	0	earl-test.log
cargo package --list --locked --workspace	0	earl-package.log
pnpm install --frozen-lockfile	0	earl-pnpm-install.log
pnpm turbo run build	0	earl-pnpm-build.log
pnpm turbo run types:check	0	earl-pnpm-types.log
pnpm audit --audit-level high	0	earl-pnpm-audit.log
git diff --check	0	local check

The first hk attempt failed while two isolated worktrees tried to install the same Rust toolchain into a new cache. I reused the already-installed external-drive toolchain and reran the full command; it passed. No check was waived.